JP5007029B2 - Grease composition and rolling bearing with grease - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a grease composition and the grease-filled bearing, and particularly for an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, an electric component such as an electric fan motor, a rolling bearing for an auxiliary machine, a rolling bearing for a motor, The present invention relates to a grease composition and a grease-filled bearing in which the grease composition is sealed.

Electrical components and accessories in automobiles, motors in industrial machines, etc. are required to be downsized, high performance, and high output year by year, and usage conditions are becoming stricter. For these, rolling bearings are used, and grease is mainly used for lubrication. However, severe use conditions such as high-speed rotation at high temperatures cause a problem in that specific peeling accompanied by a change in white structure occurs at an early stage on the rolling surface of the rolling bearing.
This specific exfoliation is different from the exfoliation from the inside of the rolling contact surface caused by normal metal fatigue, and is a fracture phenomenon that occurs from a relatively shallow portion of the surface of the rolling contact surface and is considered to be hydrogen embrittlement caused by hydrogen. As a method for preventing such a specific peeling phenomenon accompanied by a white tissue change that occurs at an early stage, for example, a method of adding a passivating agent to a grease composition is known (see Patent Document 1). A method of adding bismuth dithiocarbamate to a grease composition is known (see Patent Document 2). A method of adding an inorganic compound having an average particle size of 2 μm or less to a grease composition is known (see Patent Document 3).
However, in recent years, electrical components and accessories in automobiles, motors in industrial machines, etc., are increasingly used in rolling bearings at high temperatures, such as frequent high-speed operation-sudden deceleration operation-rapid acceleration operation-sudden stop. The method of adding a passivating agent, bismuth dithiocarbamate, and an inorganic compound has become insufficient as a measure for preventing the peeling phenomenon.
JP-A-3-210394 JP-A-2005-42102 Japanese Patent Laid-Open No. 9-217752

  The present invention has been made to cope with such problems, and by using inorganic magnesium or organic magnesium as an additive, it is possible to effectively prevent peeling on the rolling surface due to hydrogen embrittlement in a grease-filled bearing. It is an object of the present invention to provide a grease composition and a grease-filled bearing.

  The grease composition of the present invention is a grease composition obtained by blending an additive with a base grease comprising a base oil and a thickener, wherein the additive is at least selected from inorganic magnesium and organic magnesium One magnesium-based additive is contained, and the mixing ratio of the magnesium-based additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease.

The inorganic magnesium is a magnesium powder. The organic magnesium is magnesium stearate.
The thickener is a urea-based thickener.

  The grease-enclosed bearing of the present invention is a bearing in which the above-described grease composition is encapsulated.

  The grease composition of the present invention contains at least one magnesium-based additive selected from inorganic magnesium and organic magnesium in a base grease consisting of a base oil and a thickener at a predetermined ratio, so that it can be used for automobiles and industrial machinery. The occurrence of peculiar delamination due to hydrogen embrittlement seen in the bearings used can be suppressed, and the life of the grease-filled bearing can be extended.

  The grease-enclosed bearing of the present invention can effectively prevent specific peeling accompanied by a white structure change occurring on the rolling surface and has excellent bearing life. Therefore, an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, an electric fan motor, etc. It can be suitably used as a rolling bearing for automobile electrical parts, auxiliary machines, and the like.

As a result of intensive investigations into a method that can effectively prevent peeling on the rolling surface due to hydrogen embrittlement for rolling bearings, a grease composition containing at least one magnesium-based additive selected from inorganic magnesium and organic magnesium is enclosed. A rapid acceleration / deceleration test using the above-mentioned rolling bearings revealed that the bearing life can be extended.
By blending the above magnesium-based additive, it is possible that inorganic magnesium or organic magnesium reacts on the frictional wear surface or the newly formed metal surface exposed by wear and a magnesium compound film is formed on the bearing rolling surface along with iron oxide. As a result of surface analysis of the running surface. This iron oxide and magnesium compound coating formed on the rolling surface of the bearing suppresses the generation of hydrogen due to the decomposition of the grease composition and prevents unique peeling due to hydrogen embrittlement, thus extending the life of the rolling bearing. Conceivable. The present invention is based on these findings.

Examples of inorganic magnesium that can be used in the grease composition of the present invention include magnesium powder, magnesium carbonate, magnesium chloride, magnesium nitrate and hydrates thereof, magnesium sulfate, magnesium fluoride, magnesium bromide, magnesium iodide, magnesium oxyfluoride, Magnesium oxychloride, magnesium oxybromide, magnesium oxyiodide, magnesium oxide and its hydrate, magnesium hydroxide, magnesium selenide, magnesium telluride, magnesium phosphate, magnesium oxyperchlorate, magnesium oxysulfate, sodium magnesium acid , Magnesium titanate, magnesium zirconate, magnesium molybdate, etc., but in the present invention, particularly preferred is excellent heat resistance and durability, and thermal decomposition. Hard to reason, magnesium powder high-pressure effect electrode.
These inorganic magnesium may be added to grease by mixing one type or two types.

  The organic magnesium that can be used in the grease composition of the present invention is preferably an organic acid magnesium. As the organic acid constituting the organic acid magnesium, any aromatic organic acid, aliphatic organic acid, or alicyclic organic acid can be used.

Examples of organic acids are formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, 2-ethylhexylic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid Monovalent saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, monounsaturated fatty acids such as acrylic acid, crotonic acid, undecylenic acid, oleic acid, gadreic acid, Malonic acid, methylmalonic acid, succinic acid, methylsuccinic acid, dimethylmalonic acid, ethylmalonic acid, glutaric acid, adipic acid, dimethylsuccinic acid, pimelic acid, tetramethylsuccinic acid, suberic acid, azelaic acid, sebacic acid, brassic acid Divalent saturated fatty acids such as fumaric acid, maleic acid, oleic acid, etc. Examples thereof include fatty acid derivatives such as Japanese fatty acid, tartaric acid and citric acid, aromatic organic acids such as benzoic acid, phthalic acid, trimellitic acid and pyromellitic acid, and alicyclic organic acids such as naphthenic acid. Of these, stearic acid having excellent lubricity is preferably used.
These organic acids can be used alone or as a mixture.

Base oils that can be used in the present invention include mineral oils such as spindle oil, refrigerator oil, turbine oil, machine oil, dynamo oil, highly refined mineral oil, liquid paraffin, polybutene, GTL oil synthesized by the Fischer-Tropsch process, poly- Hydrocarbon synthetic oil such as α-olefin oil, alkylnaphthalene, alicyclic compound, or natural oil, polyol ester oil, phosphate ester oil, polymer ester oil, aromatic ester oil, carbonate ester oil, diester oil, Non-hydrocarbon synthetic oils such as polyglycol oil, silicone oil, polyphenyl ether oil, alkyldiphenyl ether oil, alkylbenzene oil, and fluorinated oil can be used.
Among these, it is preferable to use alkyl diphenyl ether oil and poly-α-olefin oil which are excellent in heat resistance and lubricity.

Thickeners that can be used in the present invention include benton, silica gel, fluorine compounds, lithium soap, lithium complex soap, strong lucium soap, calcium complex soap, aluminum soap, aluminum complex soap, and other soaps, diurea compounds, polyurea compounds, etc. These urea compounds are mentioned.
Of these, urea compounds are desirable in view of heat resistance, cost, and the like.

A urea compound is obtained by reacting an isocyanate compound and an amine compound. In order not to leave a reactive free radical, the isocyanate group of the isocyanate compound and the amino group of the amine compound are preferably blended so as to be approximately equivalent.
Base grease for blending various compounding agents by blending a base compound with a base oil can be obtained. The base grease is produced by reacting an isocyanate compound and an amine compound in a base oil.

  A diurea compound is obtained by reaction of a diisocyanate and a monoamine, for example. Examples of the diisocyanate include phenylene diisocyanate, tolylene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc., and monoamines include octylamine, dodecylamine, hexadecylamine, stearylamine, Examples include oleylamine, aniline, p-toluidine, cyclohexylamine and the like. The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, And diaminodiphenylmethane.

  The blending ratio of the thickener to the base grease is 1 to 40 parts by weight, preferably 3 to 25 parts by weight, based on 100 parts by weight of the base grease. If the content of the thickener is less than 1 part by weight, the thickening effect will be reduced, making it difficult to make grease, and if it exceeds 40 parts by weight, the resulting base grease will be too hard and the desired effect will not be obtained. Become.

The blending ratio of at least one magnesium-based additive selected from inorganic magnesium and organic magnesium is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. That is, (1) When the magnesium-based additive is only inorganic magnesium, 0.05 to 10 parts by weight of inorganic magnesium with respect to 100 parts by weight of the base grease, (2) When the magnesium-based additive is only organic magnesium, 0.05 to 10 parts by weight of organic magnesium with respect to 100 parts by weight of grease (3) When the magnesium-based additive is inorganic magnesium and organic magnesium, inorganic magnesium and organic magnesium are added to 100 parts by weight of base grease. Combine 0.05 to 10 parts by weight.
When the blending ratio of the magnesium-based additive is less than the above blending range, peeling on the rolling surface due to hydrogen embrittlement cannot be effectively prevented. If the above range is exceeded, abnormal wear occurs.

  In addition to a magnesium-based additive, a known grease additive may be included as necessary. Examples of the additives include antioxidants such as organic zinc compounds, amines, and phenolic compounds, metal deactivators such as benzotriazole, viscosity index improvers such as polymethacrylate and polystyrene, molybdenum disulfide, and graphite. Examples thereof include solid lubricants, metal sulfonates, antirust agents such as polyhydric alcohol esters, friction reducing agents such as organic molybdenum, oily agents such as esters and alcohols, and antiwear agents such as phosphorus compounds. These can be added alone or in combination of two or more.

  Since the grease composition of the present invention can suppress the occurrence of peculiar peeling due to hydrogen embrittlement, the life of the grease-sealed bearing can be improved. For this reason, ball bearings, cylindrical roller bearings, tapered roller bearings, spherical roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, thrust spherical roller bearings, etc. Can be used as grease.

A bearing in which the grease composition of the present invention is enclosed will be described with reference to FIG. FIG. 1 is a cross-sectional view of a deep groove ball bearing.
In the grease-filled bearing 1, an inner ring 2 having an inner ring rolling surface 2a on the outer peripheral surface and an outer ring 3 having an outer ring rolling surface 3a on the inner peripheral surface are arranged concentrically, and the inner ring rolling surface 2a and the outer ring rolling surface 3a are arranged. A plurality of rolling elements 4 are arranged between the two. The cage 5 is configured to hold the plurality of rolling elements 4, and the seal member 6 is fixed to the outer ring 3 or the like. A grease composition 7 is enclosed at least around the rolling element 4.

Examples 1-2, Reference Examples 1-2
In half of the base oil shown in Table 1, 4,4-diphenylmethane diisocyanate (trade name Millionate MT, manufactured by Nippon Polyurethane Industry Co., Ltd., hereinafter referred to as MDI) is dissolved in the ratio shown in Table 1, and the remaining half of A monoamine that was twice the equivalent of MDI was dissolved in the base oil. The respective blending ratios and types are shown in Table 1.
A solution in which monoamine was dissolved was added while stirring the solution in which MDI was dissolved, and then the reaction was continued for 30 minutes at 100 to 120 ° C. to produce a diurea compound in the base oil.
To this, a magnesium-based additive and an antioxidant were added at a blending ratio shown in Table 1, and the mixture was further stirred at 100 to 120 ° C. for 10 minutes. Thereafter, the mixture was cooled and homogenized with three rolls to obtain a grease composition.

In Table 1, the synthetic hydrocarbon oil used as the base oil is Nippon Steel Chemical's trade name Sinfluid 801 with a kinematic viscosity of 47 mm ² / sec at 40 ° C, and the alkyl diphenyl ether oil has a kinematic viscosity at 40 ° C of 97 mm ² / sec. No. Matsumura Oil Co., Ltd. trade name Moresco High Lube LB100 was used. Moreover, Sumitomo Chemical Co., Ltd. brand name hindered phenol was used for antioxidant.

  The obtained grease composition was subjected to a rapid acceleration / deceleration test. Test methods and test conditions are shown below. The results are shown in Table 1.

Rapid Acceleration / Deceleration Test A rapid acceleration / deceleration test was performed on a rolling bearing with internal rotation that supports the rotating shaft of an alternator, which is an example of an electrical accessory. The rapid acceleration / deceleration test conditions were set such that the load applied to the pulley attached to the tip of the rotating shaft was 3234 N and the rotation speed was 0 to 18000 rpm. Then, abnormal peeling occurred in the bearing, and the time when the generator stopped when the vibration of the vibration detector exceeded the set value was measured.

Comparative Examples 1-4
By the method according to Example 1, the thickener and base oil were selected at the blending ratios shown in Table 1 to adjust the base grease, and further additives were blended to obtain a grease composition. The obtained grease composition was evaluated by performing the same test as in Example 1. The results are shown in Table 1.

  As shown in Table 1, each example is excellent in a rapid acceleration / deceleration test because it can effectively prevent specific peeling accompanied by a white tissue change occurring on the rolling surface. All the rapid acceleration / deceleration tests in each example showed 300 hours or more.

  Since the grease composition of the present invention can effectively prevent specific peeling accompanied with white structure change occurring on the rolling surface and has excellent bearing life, such as an alternator, an electromagnetic clutch for a car air conditioner, an intermediate pulley, an electric fan motor, etc. It can be used for automotive electrical parts, rolling bearings for auxiliary machines, and motor bearings.

It is sectional drawing of a deep groove ball bearing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Grease-filled bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease composition

Claims (3)

A base oil, Ri name by blending an additive to a base grease comprising a thickener, a grease composition for use enclosed in the rolling bearing,
The base oil includes at least an alkyl diphenyl ether oil, and the thickener is a urea compound.
The additive contains magnesium powder as a magnesium additive, and the blending ratio of the magnesium additive is 0.05 to 10 parts by weight with respect to 100 parts by weight of the base grease. A greased rolling bearing grease composition is sealed, greased rolling bearing wherein the grease composition is a grease composition of claim 1, wherein.   The grease-filled rolling bearing according to claim 2, wherein the grease-filled rolling bearing is a bearing used for an electrical component and an auxiliary machine in an automobile or a motor in an industrial machine.

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